1. Field of the Invention
The present invention relates to an I/O card, electronic equipment using the I/O card, and a procedure for starting up the electronic equipment.
2. Description of the Related Art
In recent years, lots of digital still cameras have been commercialized as one type of peripheral equipment for use with computers. As for a procedure for taking image data produced by a digital still camera into a computer, each of the procedures described below has been adopted.
1. A digital still camera has a slot accommodating a PC card. A memory card is mounted in the slot in order to save data therein. The demounted memory card is then mounted in a computer in order to load the data from the card into the computer. In this procedure, mounting or demounting the card is achieved manually. As for the card slot, a card slot conformable to the PCMCIA standard is often adopted.
2. A camera and computer are interconnected using an interface cable, whereby data is transferred directly. In this case, an interface connector formed in the camera must be compact. An interface connector compatible with the RS-232C standard is therefore often employed.
3. A camera is connected to a conversion adaptor via a dedicated interface. For connecting the conversion adaptor to a computer, an interface of a standard rating such as a parallel interface is employed.
On the other hand, as the PC card, not only a memory card but also an I/O card has come to be commercialized recently. For data transfer from a digital still camera to a computer, a procedure of connecting the digital camera to the computer via such an I/O card is conceivable as a fourth procedure.
The foregoing procedures are concerned with data transfer. For operating a camera at a computer, second and third connections are needed.
However, transferring image data to a computer or operating a camera at a computer according to any of the three foregoing procedures of the prior art has problems, described below.
According to the first procedure, data transfer is carried out manually. Every time a memory card is filled with data, the card must be mounted and demounted. When photography is carried out intermittently with a camera set up, the camera must be moved at every mounting and demounting. This means that the position of the image is shifted often.
Moreover, an intermittent photography time is restricted by the storage capacity of a memory. The first procedure can therefore be said to be effective for random photography that is usually carried out using a silver-film camera.
A digital still camera that can be controlled remotely when connected to a computer and can transfer data directly to or from the computer is promising as peripheral equipment for computers. However, when the camera is connected to the computer according to any of the second to fourth procedures, problems described below occur.
To begin with, according to the second procedure, a camera uses its own battery as a power source. The operating time of the camera therefore depends on the longevity of the battery. The power supply of the camera must therefore be manually turned on or off from time to time in order to prevent the battery from being used up prematurely. For reducing consumption of the battery power, some cameras have a facility for turning off the power supply when no action instruction is issued to the camera for a specified time. However, when such a camera is connected directly to a computer, this facility merely increases the bother to the user, and to avoid this, the camera can only be placed immediately close to the computer and the user. The concept of remote control thus cannot be fully embodied.
The fourth procedure has the same problem as the second procedure.
It is the third procedure that alleviates the above problem. An interface conversion adaptor to be employed is therefore requested to receive power from an AC power supply. The employment of the interface conversion adaptor enables power supply to a camera. A signal line over which a start-up instruction is transmitted is included as one of several transmission lines linking the conversion adaptor and camera, whereby power management to be executed at a computer can be achieved.
However, this procedure requires incorporation of an AC-to-DC conversion circuit or provision of a separate AC-to-DC conversion adaptor. This poses a problem that either the interface conversion adaptor becomes large in size, or the number of entities connected to the adaptor increases. Moreover, a plurality of cables are needed to connect the entities. For this reason, a set of equipment for converting one interfacing specification into another becomes expensive. Moreover, connections among the camera, adaptor, and computer become complex.
Moreover, the digital still camera must cope with the necessity of being connected to a computer as well as the necessity of recording multiple images. For coping with these necessities, the storage capacity of a built-in memory of the camera is insufficient. An external memory such as a memory card is therefore employed. For this reason, the camera is provided with both an interface terminal and memory card slot. This leads to a large size of the camera and a large circuit scale. Consequently, the cost of the camera increases.